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                                                                    EXHIBIT 31.1

                                 CERTIFICATIONS

I, Sherri C. Oberg, certify that:

         1.       I have reviewed this quarterly report on Form 10-Q of
                  Acusphere, Inc.;

         2.       Based on my knowledge, this report does not contain any untrue
                  statement of a material fact or omit to state a material fact
                  necessary to make the statements made, in light of the
                  circumstances under which such statements were made, not
                  misleading with respect to the period covered by this report;

         3.       Based on my knowledge, the financial statements, and other
                  financial information included in this report, fairly present
                  in all material respects the financial condition, results of
                  operations and cash flows of the registrant as of, and for,
                  the periods presented in this report;

         4.       The registrant's other certifying officers and I are
                  responsible for establishing and maintaining disclosure
                  controls and procedures (as defined in Exchange Act Rules
                  13a-15(e) and 15d-15(e)) for the registrant and we have:

                           a)       Designed such disclosure controls and
                                    procedures, or caused such disclosure
                                    controls and procedures to be designed under
                                    our supervision, to ensure that material
                                    information relating to the registrant,
                                    including its consolidated subsidiaries, is
                                    made known to us by others within those
                                    entities, particularly during the period in
                                    which this report is being prepared;

                           b)       [Paragraph omitted in accordance with SEC
                                    transition instructions contained in SEC
                                    Release No. 34-47986];

                           c)       Evaluated the effectiveness of the
                                    registrant's disclosure controls and
                                    procedures and presented in this report our
                                    conclusions about the effectiveness of the
                                    disclosure controls and procedures, as of
                                    the end of the period covered by this report
                                    based on such evaluation; and

                           d)       Disclosed in this report any change in the
                                    registrant's internal control over financial
                                    reporting that occurred during the
                                    registrant's most recent fiscal quarter (the
                                    registrant's fourth fiscal quarter in the
                                    case of an annual report) that has
                                    materially affected, or is reasonably likely
                                    to materially affect, the registrant's
                                    internal control over financial reporting;
                                    and

         5.       The registrant's other certifying officers and I have
                  disclosed, based on our most recent evaluation of internal
                  control over financial reporting, to the registrant's auditors
                  and the audit committee of the registrant's board of directors
                  (or persons performing the equivalent functions):

                           a)       All significant deficiencies and material
                                    weaknesses in the design or operation of
                                    internal control over financial reporting
                                    which are reasonably likely to adversely
                                    affect the registrant's ability to record,
                                    process, summarize and report financial
                                    information; and

                           b)       Any fraud, whether or not material, that
                                    involves management or other employees who
                                    have a significant role in the registrant's
                                    internal control over financial reporting.

Date: November 12, 2003

                                             /s/ Sherri C. Oberg
                                             --------------------------------
                                             Sherri C. Oberg
                                             Chief Executive Officer
                                             (Principal Executive Officer)